摘要
对油菜茎象甲在白菜型油菜不同播期密度下发生危害程度的调查结果:油菜播期晚,害虫平均虫口数大,被害严重。西宁地区4月上旬以后播种的油菜被害率较高,达28.0%以上;随种植密度增大,油菜被害率呈上升趋势,在高密度225万株/hm^2时被害最严重。
The occurrence of rape stem weevil(Ceuthorrhynchus asper Roel) was studied in different sowing times and densities of spring rape(Brossica campestris L.) .The results showed there were heavier damages in cases of late sowing time and higher sowing density. In Xining the damage rate reached above 28% after the first ten days of April. The damage became worse when sowing density was enlarged, and there was the heaviest damage at the highest density of 225 × 104 plants/hm2. It's necessary to sow early properly and to control density strictly in practice.
出处
《青海大学学报(自然科学版)》
1999年第2期35-37,53,共4页
Journal of Qinghai University(Natural Science)